The invention relates to a mobile radio elephone set comprising at least one control processor and at least one signal processor which are at least occasionally not in an active mode.
Such a mobile radio telephone set is known from EP 0 343 528 in which a battery-operated mobile telephone is described which comprises mainly a control section and a radio section. The control section comprises a processor unit which carries out first control functions and a logic LSI unit (Large Scale Integration) for second control functions. The first control functions are often not used then, but are complicated and require a high supply rate. The second control functions are constantly used and often work at a low supply rate. To reduce the energy consumption of the mobile telephone, the processor unit always carries out the first control functions only when a function is to be carried out. In the rest of the time the processor unit is in the stop mode (column 4, lines 17-28). If necessary, the LSI unit intermittently adds thereto the processor unit by switching-on a high supply rate. For this purpose, the LSI unit is to use part of its capacity for continuous active monitoring of the processor unit in that the necessity of the processor unit is queried (see FIG. 2 with associated description, column 4, lines 29-34). Furthermore, the processor unit cannot become active by itself because a fast supply rate is directly required, but is to wait for an assignment by the LSI unit. More particularly in the case of a plurality of processors operating independently of each other, the monitoring of the individual units in mobile telephones according to the state of the art is very costly and not the most favorable solution as regards energy consumption of the mobile telephone.
Therefore, it is an object of the invention to reduce in a most simple manner the energy consumption in a mobile radio telephone set.
The object is achieved according to the invention in that a control unit selects operating modes at least for the control processor and/or the signal processor. When a separate control unit is used, particularly two or more coupled processors or other circuit elements of the whole mobile radio telephone set may be controlled independently of each other. Each coupled unit may directly be set to its own operating mode to thus drive only the units that are currently necessary and thus reduce the energy consumption. The control unit may then be realized preferably by a hardwired combinatorial and clocked logic which works in a highly energy-saving manner. But also any other realization offers the advantage according to the invention without leaving the scope of protection of the main claim.
In an advantageous embodiment of the invention at least the control processor or the signal processor comprises at least two sub-blocks and the control unit selects an operating mode by switching on/off at least one sub-block. The processors (or other circuit units) of the mobile radio telephone set may be formed by of separate sub-blocks (usually at least by processor core and input/output unit or interface) which may each be switched separately.
In an extension of the mobile radio telephone set according to the invention at least the control processor or the signal processor transmits request signals to the control unit by signal buses. The processors are coupled to the control unit by signal buses. By transmitting request signals on the signal bus which signals may contain, for example, certain signal combinations, the processors (or other circuit units) request a certain operating mode. The operating modes are featured by the sub-blocks that are switched on or off, respectively.
In one embodiment the control unit selects the operating modes in dependence on the request signals by switching on/off the supply clocks for the sub-blocks. As the sub-blocks especially in mobile radio telephone sets are usually clocked processors, an energy-saving operating mode is achieved especially by switching off the supply rates. Since each sub-block receives its own supply clock, the respective sub-block may be switched on or off by switching the supply clocks on or off and thus the various operating modes can be set for the processors and thus also for the whole mobile radio telephone set.
In a highly suitable embodiment of the invention, at least one processor includes as sub-blocks at least one processor core supplied with a core clock and at least one interface supplied with an interface clock Logical operations and calculations are carried out in the processor core. The interface is the general input/output unit (I/O unit) of the processor which processes all the tasks in correlation with the communication with other units of the mobile radio telephone set. Both sub-blocks are clocked units and are supplied with a clock by separate transmission lines irrespectively of each other. The frequency of the core clock may then also deviate from that of the interface clock.
For a further embodiment of the invention at least one wake-up counter monitors an operating mode of at least one processor, which operating mode is featured by a switched-off core clock and interface clock, and transmits a respective request signal for changing to an active mode of at least one processor which active mode is featured by a switched-on core clock and interface clock. Wake-up counters are clocked counters which are usually written with a value (wake-up value) and then decremented for initiating actions at specific counts. The wake-up value indicates the time in which the assigned processor is not used and may therefore be set to a stop mode or sleep mode by switching off the sub-blocks. More particularly in mobile radio telephone sets for TDMA mobile radio systems the wake-up value is in many cases a multiple of the frame in which the data transmission is organized. In this manner, control operations may be initiated inside the mobile radio telephone set in dependence on the count. For example, the processor is activated when the count is xe2x80x9czeroxe2x80x9d, whereas the power supply for memories (ROM) coupled to this processor is switched on already three frames earlier, so that a steady state is found at the wake-up instant. For this purpose, one or more registers are assigned to a wake-up counter, which registers may be programmed with certain counts. A comparator compares the current count with the register contents and when they match causes a respective request signal to be sent to the control unit by the signal bus. The control unit switches on the required unit of the mobile radio telephone set in accordance with the request signal (first the supply clock for the memory and in the case of the respective request signal for the processor). In addition to the wake-up counter, the procedure for switching on a processor may be initiated by an interrupt if there is an unforeseen event (for example, a connection set-up to or from another subscriber). This procedure is then controlled by the control unit preferably after a request signal from the interface.
In a preferred embodiment of the invention the control unit switches off a reference clock for all the coupled processors when the core clock and interface clock are switched off. When all the processors for which the control unit selects the operating mode by switching on/off sub-blocks are not needed, also the oscillator which produces the reference clock may be switched off. The supply clocks are recovered from the reference clock which supply clocks are switched on/off for the individual sub-blocks by the control unit. More particularly, when sub-blocks are switched off, a distinction may be made between the two operating modes, the stop mode and sleep mode of the processors, the sleep mode being characterized in that, additionally, it is also permitted to switch off the reference clock.
These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.